Peter Hayes has written a superb new book examining how and why the Holocaust happened.
Targets: Why the Jews?
Attackers: Why the Germans?
Escalation: Why Murder?
Annihilation: Why This Swift and Sweeping?
Victims: Why Didn't More Jews Fight Back More Often?
Homeland: Why Did Survival Rates Diverge?
Onlookers: Why Such Limited Help from Outside?
Why? Explaining the Holocaust is hard to read but it does provide answers to questions that have puzzled us for decades.